1. Field of the Invention
The invention relates to an automation appliance having a terminal module into which a function module can be plugged, the automation appliance being suitable for modular extension by arranging further terminal modules in a row, where the terminal module comprises a first holding device for holding the function module, a second holding device which has a first contact device, for holding a connecting module which has a second contact device, and where a supply voltage for the function module is passable through the connecting module.
2. Description of the Related Art
EP 1 764 873 A1 discloses a conventional automation appliance which can be constructed in a modular form, where the terminal module can make contact with a function module, and the terminal module can be connected to an adjacent terminal module.
DE 198 07 710 C2 also discloses a conventional automation appliance having a terminal module, function modules and a connecting module, where a supply voltage does not pass through the connecting module.
In such conventional automation appliances, which are preferably used to control industrial processes using a decentralized peripheral, a supply voltage for the individual terminal modules, into which function modules are in turn plugged, is provided by feed modules. For the purposes of the disclosed invention, a function module should be understood to mean, for example, an input/output assembly for application of input/output signals from the industrial process. In accordance with conventional automation appliances, the feed modules are plugged into a free plug slot from a terminal module, and then supply a group of further terminal modules that are connected to the feed module and in turn contain further function modules. Here, the load groups are formed by arranging the corresponding terminal modules in a row, and all the modules within one load group are fed from the same power supply unit. In the case of the automation appliance of DE 198 07 710 C2, as explained at paragraph 20 thereof, supply voltage is looped through the terminal modules from one terminal module to another.
This has the disadvantage that the feed modules each occupy their own plug slot, and changes to a supply voltage group or else a load group results in a group such as this being disconnected. A further disadvantage is that this plug slot is lost for actual automation tasks, which are intended to be performed by the function modules. In the past, various variants have been known for the modular design of such appliances in automation technology, for how to supply a supply voltage to a channel module or technology module. With these solutions, however, it is always necessary to sacrifice a “free” plug slot for a feed module.